1. Field of the Invention
The present invention relates to an X-ray examination method and an X-ray examination apparatus. In particular, the present invention relates to a photographing method for examining an object using X-ray irradiation, which is a technique applicable to an X-ray examination method and an X-ray examination apparatus.
2. Description of the Related Art
Recently, with high integration of an LSI (Large-Scale Integration) by submicron microfabrication technique, functions which were conventionally divided into a plurality of packages can now be integrated into one LSI. Since the increase in the number of pins that arise as a result of incorporating the functions necessary for one package cannot be responded with the conventional QFP (Quad Flat Package) and PGA (Pin Grid Array), LSIs of BGA (Ball Grid Array) and CSP (Chip Size Package) package, in particular, are recently being used. The BGA package is used where ultraminiaturization is necessary such as a mobile phone even if the required number of pins is not large.
The BGA and CSP package of LSI greatly contributes to ultraminiaturization, but has a feature that the solder portion and the like cannot be seen from the outer appearance after assembly. When inspecting a printed board and the like mounted with the BGA or CSP package, the quality determination is performed by analyzing a transmitted image obtained by irradiating an object to be examined with an X-ray.
For instance, Japanese Laid-Open Patent Publication No. 2000-46760 discloses an X-ray sectional examination apparatus capable of obtaining a clear X-ray image by using an X-ray planar sensor to detect the transmitted X-ray.
Japanese Laid-Open Patent Publication No. 2003-344316 discloses a method of reconstructing an image in an inclined three-dimensional X-ray CT by appropriately selecting the irradiation angle of the X-ray.
Japanese Laid-Open Patent Publication No. 2006-162335 discloses an X-ray examination apparatus capable of performing a two-dimensional examination based on an X-ray image acquired with parallel X-ray detection means and a three-dimensional examination based on an X-ray image acquired with inclined X-ray detection means to perform both the examinations at a high speed.
Japanese Laid-Open Patent Publication No. 06-100451 discloses an automatic laminographic system for creating a cross-sectional image of a connecting part of an electronic component, automatically identifying a fault of the connecting part and finding the position by the analysis system, and determining process characteristics of the connecting part.
However, in the X-ray photographing technique relating to the conventional X-ray examination described above, time is required for imaging and 3D (reconstruction) calculation if the area of an examination area that can be reconstructed is increased. For instance, in order to examine a printed board and the like as described above, images of a plurality of specific portions will suffice in most cases, instead of an image of the entire examination target. In this case, when portions to be examined in the target of examination are arranged in a scattered state, it is not efficient to prepare an X-ray detector having an area (or volume) that encompasses the entire region as the target of examination from the viewpoint of enlargement in device, increase in calculation load, and the like.
An imaging system or an examination target workpiece needs to be moved to change the examination area, whereby movable portions increase. Thus, problems in cost, maintenance, and reliability arise.
Furthermore, when changing the examination area in a case where the area of the examination target is large (e.g., a glass substrate), it is sometimes difficult to move the workpiece side in the X-Y direction or rotate the same over 360 degrees.